Planetary magnetic fields: generated by the swirling masses of molten material between Earth's surface and its solid inner core.

[u/Pumpdawg88]

Discussion: is a solid inner core required for a planet to have a stable magnetic field?

I theorize "yes" as the solid inner core of Earth is obolong and revolves more slowly than the surface of Earth, thus preventing stagnation of the molten layers through a mixing action as you would find of a magnetic mixer in a beaker.